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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Souptick Joarder <jrdr.linux@gmail.com>,
        joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com,
        airlied@linux.ie
Cc:     intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, willy@infradead.org
Subject: Re: [PATCH] gpu: drm: i915: Change return type to vm_fault_t
In-Reply-To: <20180417151127.GA31655@jordon-HP-15-Notebook-PC>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20180417151127.GA31655@jordon-HP-15-Notebook-PC>
Date:   Tue, 17 Apr 2018 18:29:41 +0300
Message-ID: <87h8o9g8be.fsf@intel.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 17 Apr 2018, Souptick Joarder <jrdr.linux@gmail.com> wrote:
> Use new return type vm_fault_t for fault handler. For
> now, this is just documenting that the function returns
> a VM_FAULT value rather than an errno. Once all instances
> are converted, vm_fault_t will become a distinct type.
>
> Reference id -> 1c8f422059ae ("mm: change return type to
> vm_fault_t")
>
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h |  3 ++-
>  drivers/gpu/drm/i915/i915_gem.c | 15 ++++++++-------
>  2 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a42deeb..95b0d50 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -51,6 +51,7 @@
>  #include <drm/drm_gem.h>
>  #include <drm/drm_auth.h>
>  #include <drm/drm_cache.h>
> +#include <linux/mm_types.h>
>
>  #include "i915_params.h"
>  #include "i915_reg.h"
> @@ -3363,7 +3364,7 @@ int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,
>  			   unsigned int flags);
>  int __must_check i915_gem_suspend(struct drm_i915_private *dev_priv);
>  void i915_gem_resume(struct drm_i915_private *dev_priv);
> -int i915_gem_fault(struct vm_fault *vmf);
> +vm_fault_t i915_gem_fault(struct vm_fault *vmf);
>  int i915_gem_object_wait(struct drm_i915_gem_object *obj,
>  			 unsigned int flags,
>  			 long timeout,
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index dd89abd..bdac690 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1882,7 +1882,7 @@ int i915_gem_mmap_gtt_version(void)
>   * The current feature set supported by i915_gem_fault() and thus GTT mmaps
>   * is exposed via I915_PARAM_MMAP_GTT_VERSION (see i915_gem_mmap_gtt_version).
>   */
> -int i915_gem_fault(struct vm_fault *vmf)
> +vm_fault_t i915_gem_fault(struct vm_fault *vmf)
>  {
>  #define MIN_CHUNK_PAGES ((1 << 20) >> PAGE_SHIFT) /* 1 MiB */
>  	struct vm_area_struct *area = vmf->vma;
> @@ -1895,6 +1895,7 @@ int i915_gem_fault(struct vm_fault *vmf)
>  	pgoff_t page_offset;
>  	unsigned int flags;
>  	int ret;
> +	vm_fault_t retval;

What's the point of changing the name? An unnecessary change.

BR,
Jani.

>
>  	/* We don't use vmf->pgoff since that has the fake offset */
>  	page_offset = (vmf->address - area->vm_start) >> PAGE_SHIFT;
> @@ -2000,7 +2001,7 @@ int i915_gem_fault(struct vm_fault *vmf)
>  		 * and so needs to be reported.
>  		 */
>  		if (!i915_terminally_wedged(&dev_priv->gpu_error)) {
> -			ret = VM_FAULT_SIGBUS;
> +			retval = VM_FAULT_SIGBUS;
>  			break;
>  		}
>  	case -EAGAIN:
> @@ -2017,21 +2018,21 @@ int i915_gem_fault(struct vm_fault *vmf)
>  		 * EBUSY is ok: this just means that another thread
>  		 * already did the job.
>  		 */
> -		ret = VM_FAULT_NOPAGE;
> +		retval = VM_FAULT_NOPAGE;
>  		break;
>  	case -ENOMEM:
> -		ret = VM_FAULT_OOM;
> +		retval = VM_FAULT_OOM;
>  		break;
>  	case -ENOSPC:
>  	case -EFAULT:
> -		ret = VM_FAULT_SIGBUS;
> +		retval = VM_FAULT_SIGBUS;
>  		break;
>  	default:
>  		WARN_ONCE(ret, "unhandled error in i915_gem_fault: %i\n", ret);
> -		ret = VM_FAULT_SIGBUS;
> +		retval = VM_FAULT_SIGBUS;
>  		break;
>  	}
> -	return ret;
> +	return retval;
>  }
>
>  static void __i915_gem_object_release_mmap(struct drm_i915_gem_object *obj)
> --
> 1.9.1
>

-- 
Jani Nikula, Intel Open Source Technology Center